The invention relates to a housing construction for receiving or accommodating and supporting a micro pump conveying for example a fluid, the micro pump working according to the principle described in WO-A 97/12147; as far as the operation method of this type of pump or of a corresponding type of a fluidic motor is concerned, reference is explicitly made to this document, particularly to page 1 (paragraph 2), page 5 (paragraph 4) and page 6 (last paragraph) as well as page 7 (first paragraph). An inner wheel and an outer wheel are designed and arranged to be in a meshing engagement with each other, both, the inner wheel and said outer wheel being rotatably arranged in a sleeve, compare FIGS. 1, 1a, 2 and 2a, as well as FIGS. 3a, 3b and 3c of this document. The inner wheel is coupled with a shaft (50) to be stiff against torsion. An axis of the outer wheel and of the sleeve is offset relative to an axis of the shaft, so that the inner wheel with its outward oriented teeth rolls on an inward oriented, smooth, particularly cycloid tooth structure of the outer wheel, and axial sealing lines are provided depending on the number of teeth, respective pairs of said sealing lines defining a conveying chamber. In a pump arrangement, the conveying chambers enlarge in a direction of rotation on a suction side, take up a fluid and convey it to a delivery side over an imagined center plane extending through an axis, on which delivery side the conveying chamber, which just passed over, continuously decreases in the course of a continued rotation until it is practically zero, and returned to the suction side on an opposite side of the center plane. On the suction side, the pump chamber starts to open again continuously with the rotary movement, so that the cycle is concluded. The movement described for one conveying chamber is simultaneously valid for all existing conveying chambers which at an instant have a different volume between a respective pair if sealing lines, so that, upon operating the pump, a fluid current of a maximum uniformity together with a high ability of miniaturization of the entire micro system construction is achieved.
A high miniaturization requires that fluidic micro systems, which are e. g. designed as pumps, are correspondingly supported or arranged. Thus, in the described prior art according to WO-A 97/12147, a sleeve is selected as a bearing, in which sleeve parts (41, 42) are inserted on both face ends of the inner wheel and the outer wheel, the parts serving for supporting the shaft and for determining an inlet kidney and an outlet kidney (specifically described in FIG. 8 of the document with reference to an inlet kidney 41k and an outlet kidney 42k). The inlet kidney is offset (reflected) at an angle of 180xc2x0 relative to the outlet kidney, but on two opposite ends, so that an axial fluid current is obtained from the inlet kidney to the outlet kidney over the conveying chambers continuously changing in volume according to the above mentioned description. However, such a pump may also operate with a U-shaped fluid current, the inlet kidney and the outlet kidney in this case being arranged at the same face end of the pump, only offset to be mirror-inverted at an angle of 180xc2x0 relative to each other (reflected at a center plane extending through an axis). Such a micro system can be inserted or insertable in a housing construction such that it is safely and exactly supported, but that simultaneously all connections are provided for permitting a fluid inlet, a fluid outlet and a coupling of a mechanical driving source for rotating a pump shaft (of an inner wheel pump or an outer wheel pump) or an output or delivery drive shaft (of a fluidic motor) or a measurement technical aspect (of a fluidic sensor) for the flow of a volume.
A suitable housing shape for accommodating such a micro pump is described in a data sheet xe2x80x9cPumpenkopf mzr(copyright)-4600xe2x80x9d by Hydraulik Nord Parchim Mikrosysteme GmbH. The pump head described in this document is provided with a shaft protruding at a face end four coupling a motor. This housing construction comprises five disc-shaped elements adapted as cylindrical elements, starting with a housing-shaft sealing, a compensating kidney plate and a rotor support plate, followed by a fluid guiding means and a terminal end cover. The rotor support has a thickness (or height or size extending in an axial direction) corresponding to an axial dimension of the outer wheel and the inner wheel according to the above mentioned description. The support plate is provided with an opening offset relative to the shaft axis for eccentrically driving the inner wheel, so that the outer wheel of the toothed ring micro pump is supported eccentrically in the opening of the plate and realizes the above described operating method of conveying chambers continuously increasing in volume and on an opposite side continuously decreasing in volumexe2x80x94when the shaft is driven by a rotating drive. On both sides of the outer wheel and the inner wheel, thus in a direct contact with the wheels at a face end respectively, the compensating kidney plate and the fluid guiding plate are arranged, the plates comprising the above described inlet kidney and outlet kidney on a fluid supplying side and oriented towards the rotor, and compensating kidneys arranged to be reflected symmetrically with respect thereto for providing a hydraulic balance on an opposite side. Thus, a U-shaped fluid current is obtained extending from an inlet over the inlet kidney to the rotating pump chambers, towards an outlet and back to a radially oriented outlet as shown in the data sheet mzr(copyright)-4600.
DE-B 33 10 593 (White) shows a housing construction for a pump arrangement (FIG. 1, reference numeral 22) according to which an eccentrically operating gerotor together with an eccentrically operating wobble rod is realized. At an end through which the shaft does not pass, a central outlet and an inlet radially offset with respect to the outlet are provided, a number of intermediate plates provided with channel segments being arranged between the inlet and the outlet (compare FIGS. 2, 3, 4 and 5 of the document). DE-A 24 08 824 (McDermott, compare FIG. 4) works with only three plate shaped elements; the last mentioned illustration shows the gerotor principle in connection with a compensation of wear aspects of teeth being in a meshing engagement, whereby channel segments are provided in a directly adjacent portion between an inner plate and two outer support plates for the shaft. CH-A 661 323 (Weber) also relates to channel segments in a housing construction comprising a number of plates, the document in a modular construction manner assembling a toothed wheel pump from a number of components easy to combine, to replace and to supplement, but actually describing a housing for accommodating such a pump.
It is an object of the invention to improve a housing construction such that the flexibility of the housing construction is increased and that it is not necessary to separately manufacture each of the described plate-shaped elements for each individual application.
According to the invention the object is achieved by arranging at least one and preferably two or more plate-shaped layered structure elements between a support plate for receiving or accommodating an outer element of a micro system and a connecting block for mounting inlet and outlet means, with which elements a fluid conveyance or transport in the layered structure elements, i. e. from an inlet to the micro system in the support plate (inlet channel) and back to an outlet (outlet channel), is improved and made more flexible.
At least one further plate-shaped layered structure element comprises one, two or more channel segments oriented either substantially radially, circumferentially or axially. Only axially oriented channel segments may be provided, but also only substantially radially oriented segments may be provided, as well as a combination of both channel segments provides an optional fluid guiding without requiring a modification of the support plate and without requiring an adaptation of the connecting block and its fluid supply. An adaptation is effected over at least one further plate-shaped layered structure element, thus providing a higher flexibility of the existing standard components for a fluid supply or the support plate.
The invention realizes that certain precision parts have to be used only at positions at which they are required, whereas other layered structure elements of the housing construction may be standard components; thus, for example, the connecting block for connecting flexible tubes may be a standard component not requiring a particular precision, on the contrary, a support plate for a rotor has to be provided as a precision part, and also the plate-shaped layered structure elements which are adjacent to the support plate and are provided as one of the further plate-shaped layered structure elements and one additional plate-shaped layered structure element. The two neighbored plates with respect to the support plate for e. g. a micro pump carry kidneys as described in detail before, an inlet kidney and an outlet kidney being located in one of the plates and compensating kidneys being mirror-image located in the other of the plates.
Actually, the kidneys are channel segments which have a circumferential curved extension, which may also have a uniform width, and in which a fluid is conveyed. Simultaneously, the kidneys have a continuous axial design in the xe2x80x9ckidney platexe2x80x9d on one side and in the axially symmetrical xe2x80x9ckidney platexe2x80x9d on another side of the support plate for the micro system, the kidneys having their ends at a surface of the corresponding plate or at a surface of a further plate then covering the first plate of the layered structure assembly of the housing.
Thus, two separate channels may be provided, one channel system for supplying a fluid to a micro system and a second channel system for delivering a fluid from said micro system on an outlet side (e. g. a delivery side of said micro pump), said second channel system being circumferentially offset with respect to said first channel system and mounted in said plate-shaped layered structure element. Each of said channel systems leads away from a mounting position for said micro system, e. g. said pump, both in an axial and a radial outward direction to said connecting block for mounting said inlet and outlet connections, said mounting position being located far in the center of said housing construction. Preferably, said one further plate comprises a radial and an axial channel segment in said first channel system and in said second channel system. Therefore, in one single plate-shaped element, the fluid current may strongly be offset in a radial direction to allow the use of thicker connecting means, but nevertheless to provide a shaft in a shaft support on both sides of said support plate accommodating said micro system. Thus, the shaft opening extends on both sides of said support plate, and said shaft is supported on both sides of said micro system.
The micro pump is referred to as an example. The housing construction is similarly suited for accommodating other micro systems, such as a micro motor driven by a fluid, which micro motor is driven by supplying a fluid current, and in which micro motor a delivery shaft delivers at a speed corresponding to the fluid current. A sensor having a fluid drive may also be used as a micro system, said sensor being arranged in said housing construction and measuring a fluid current, a shaft not having to extend completely out of said housing, but only being provided as a shaft end for supporting a rotor, a speed corresponding to said fluid current being scanned by optical, inductive or magnetic means. Therefore, the proposed housing has a versatile field of application for practically all micro systems working with a fluid flow rate, said micro systems being represented according to the invention by a pump, a motor and a sensor.
Axial channel segments in an additional plate-shaped layered structure element arranged directly adjacent to said support plate for said micro system may have a particular design. When their length is smaller than a height (or thickness or size) of said layered structure element, said continuous axial kidney is coupled to be laterally offset, when the diameter of said axial channel segment is larger than a maximum width of said kidney at said coupling position. A total volume of said fluid collected in said continuous axial kidney may thus be delivered easily and without flow difficulties, a flow cross-section of an opening being recommended to be selected such that it substantially corresponds to a cross-section of said kidney at a position of a maximum flow volume, which cross-section in an operation mode is interspersed by said fluid to be conveyed through said channel segments.
A maximum flow volume (volume per time) exists on both sides (suction side/delivery side) of a pump or a motor and is not constant in case of a circumferentially extending kidney, which is due to the manner of volume change of a respective conveying chamber during a rotary movement. When the axial channel segment in the further plate-shaped layered structure element is provided at a circumferential position of said kidney, particularly continuously changing its width, the supplied fluid and the delivered fluid may be axially displaced exactly to a position at which said maximum flow volume is obtained in the course of said circumferentially extending kidney. In an axial top plan view of a pump rotating clockwise, said maximum flow volume is located in a first and a second quadrant, in said first quadrant at an angle between 75xc2x0 and 85xc2x0, particularly substantially between 80xc2x0 and 85xc2x0 and correspondingly axially symmetrical in said second quadrant.
A design of a radially oriented, elongated opening through said further layered-structure element between said connecting block and said first further layered structure element comprising said kidneys is obtained by combining an axial and a substantially radial channel segment, said radial channel segment having a depth oriented in an axial direction, said depth corresponding to an axial extension of a second or further) layered structure element. Said channel segment provides a displacing function for said fluid current leading from portions close to an axis to radially more outward portions, where two adjacent connections for supplying and delivering a fluid may be arranged in said connecting block without problems.
According to the invention, slant openings or channel segments having a skew or slant orientation relative to an axis may be avoided in said layered elements. The channel segments according to the invention have a radial, circumferential or axial extension or an optional combination thereof, so that described by cylindrical coordinates, each position in said housing construction is within reach, combined by an axial channel segment, circumferential channel segment or radial channel segment respectively required. By selecting specific plates comprising corresponding channel segments, connections between standard components may be obtained without designing a whole micro system with its housing. Only layers of a layered structure construction, which layers have to be designed differently, are newly designed while maintaining the remaining layers.
The complete layered structure of said housing is axially tightened together, e. g. by center pins and/or cylinder screws inserted at an end part, at which also a mounting position is provided for a micro pump accommodated in said housing. On another axial side of said housing, connections for supplying and delivering a fluid are provided, said connections having either a radial or and axial orientation depending on the design of said connecting block.
The invention
provides a fluid transition from connecting means having relatively large dimensions to a miniaturized fluidic operational range of a micro system, such as a micro pump;
realizes a miniaturized manufacturing of toothed ring micro systems;
provides a flexible fluid conveyance in a layer structure (from a connection to a rotor), which structure is easy to manufacture;
provides a flexible design of a xe2x80x9cconnecting blockxe2x80x9d housing component for supporting different connecting means or fluid connections varying in their position;
provides a representation of flow cross-sections in structures having a 2 xc2xd dimensional extension, such as they may be provided for instance by LIGA, wire erosion, precision blanking, etching, laser, etc.;
allows expendable parts, such as bearings, to be exchanged;
allows a batch processing of a number of parts simultaneously;
allows the use of an identical semi-finished product (basic material) for all operational ranges;
allows a direct piling of a number of rotor sets.
A particularly favorable coupling embodiment for mounting a housing construction at a driving source, such as a feed-forward or feed-backward controlled drive, is realized by a coupling housing, on one side of which said housing construction with said micro pump and on the other side of which a drive assembly are mounted. Both said drive assembly and said housing construction for the micro pump are provided with a protruding collar, said collars preferably not having equal dimensions to avoid confusion of the different sides. Said collar engages in a recess exactly adapted to said collar, said two recesses in said coupling housing being exactly aligned in an axial direction relative to each other. When said pump and said drive assembly are mounted with their exactly fitting collars from both axial sides of said coupling housing, it can be guaranteed that the shafts are in an axial alignment and remain connected in said axial alignment over an adapter. Thereby, a radial offset of said shafts may be avoided; assembling is favored and accelerated. Said coupling housing may be covered by a sleeve having an outer polygonal, particularly a tetragonal or a octagonal design, from which sleeve a motor and a pump protrude on both face ends. Said coupling may also be used for other combinations of fluidic micro systems.
Thus, the invention provides clearness, easily manufacturable individual parts, facilitates manufacturing, and increases assembling flexibility and exactness. Only necessary layered structure elements have to be precision manufactured, whereas other, uncritical layered structure elements may remain as standard components. It is particularly pointed out that said layered structure elements, when they are plate-shaped, may preferably have an equal thickness (a height measured in an axial direction) and may therefore be manufactured as semi-finished products from the same plate material. The same semi-finished produce serves as a basic product for a number of layered structure elements which are arranged axially one after the other and all have equal quality features of the basic plate. A different evenness and surface quality of said basic plate is thus transferred directly to the layered structure elements manufactured from said plate and predetermine which semi-finished product should be used for which precision parts and which other semi-finished product should be used for the standard elements of the layered structure. Therefore, manufacturing costs may be reduced, an after-treatment of said precision parts being avoided and a semi-finished product involving a high cost not having to be used for all layered structure elements, which avoided methods would have resulted in an increase in the cost of the manufactured housing construction. In addition to said cost reduction, an exact fluid conveyance in said micro pump and a sealing between the individual layered structure elements as well as an exact fluid conveyance in said inlet kidneys, said outlet kidneys and said compensating kidneys are provided, said features determining the performance and the efficiency of said micro pump.
An elongated axial opening is called xe2x80x9cshaft openingxe2x80x9d for supporting said shaft, when mounting a micro system. Said opening is elongated, it extends continuously through a support plate and in both axial directions of said housing construction, said opening extending at least through said further plate-shaped layered structure, said support plate and said connecting block or said base element, at least reaching into to extend xe2x80x9ccontinuouslyxe2x80x9d. Two layered structure elements with their shaft opening portion, may serve as bearings for said shaft with a slide bearing, said elements being directly adjacent to said support plate (for said micro system). Depending on the length of said axis, an additional bearing may be provided in said base element, said bearing being designed as a rolling bearing or a slide bearing, for additionally supporting said shaft in a portion located between said supply side and said delivery side (in case of a pump and a motor or in case of a fluidic motor and a drive). Said shaft may thus be stabilized in said slide bearings, thereby increasing the service life of said bearings. In said connecting block, a shaft safety device may be provided, said device blocking an axial movement of said shaft. Said safety device is not required, when said additional bearing in said base element is provided; in this case, said shaft is not required to protrude into said connecting block, but it may terminate before, which is correspondingly valid for the shaft opening of the housing.
The above used terms of an extension in an axial direction, in a radial direction and in a circumferential direction are oriented at cylindrical coordinates, however, a plate-shaped layered structure assembly has not necessarily a cylindrical outer shape, on the contrary, also a polygonal, such as a tetragonal, a hexagonal or an octagonal outer shape, as well as not circular shapes, such as oval shapes, are comprised by the invention. Also a radial extension has to be regarded as only substantially radial. The use of the technical term xe2x80x9ccircumferentialxe2x80x9d extension serves to facilitate comprehension, but not to restrict the realization of the invention. In the same manner, the terms xe2x80x9cdiscxe2x80x9d and xe2x80x9cplatexe2x80x9d are used such that they describe a flat shape without a specifically defined outer dimension or outer shape, although it is advantageous to select a cylindrical shape being oriented at the cylindrical shape of said outer wheel of the micro pump, however this is not imperative.